Multimode engines (MM) may require different types or values of fuel properties than those used to evaluate boosted spark ignition engines. For some MM engines, fuels with a high Research Octane Number (RON) and octane sensitivity (S) are preferred. While single iso-olefins can provide high RON and S, the extent to which phi sensitivity can be manipulated is unknown. We developed and utilized a process to produce iso-olefins with a controlled degree of branching from biomass-derived oxygenates (e.g. ethanol). Catalyst formulations and process conditions (e.g. pressure, WHSV, temperature, feedstock composition) were controlled to generate mixtures of iso-olefins with a single methyl, two methyls, or many methyl substitutions. The RON and MON were measured, and a rapid compression machine was used to investigate the phi sensitivity of the mixtures of iso-olefins. RON and S increase with the degree of branching of the iso-olefins mixtures. Small concentration of impurities (&lt;5%) present in the iso-olefins mixtures have a significant and negative impact on S. Initial results indicate modifying the iso-olefin structure changes the phi sensitivity. This method is the first demonstration that phi sensitivity can be modified by changing the molecular structure of components of complex mixtures with fuel properties that are relevant for high-efficiency engines.

Controlling fuel properties by tuning degree of branching in iso-olefins mixtures

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.